1. Field of the Invention
The present invention is generally related to a marine propulsion system and, more particularly, to a marine propulsion system that comprises a first tube that encompasses a second tube with a universal joint located within the second tube and an exhaust passage defined between the first and second tubes.
2. Description of the Prior Art
Those skilled in the art of marine propulsion systems are familiar with sterndrive devices in which exhaust gases are directed from an engine location within a marine vessel, through a transom of the vessel, and through a drive unit attached to the transom so that exhaust gases can be emitted below water level or otherwise through a portion of the sterndrive structure.
U.S. Pat. No. 4,764,136, which issued to Johansson on Aug. 16, 1988, describes a marine drive means. The invention relates to a marine drive comprising a water cooled internal combustion engine mounted in a boat, a shield mounted on the transom stern of the boat and supporting a universal joint housing and a pinion box connected to the universal joint housing and comprising a propeller arranged to be immersible in the water.
U.S. Pat. No. 4,897,057, which issued to McCormick on Jan. 30, 1990, discloses a marine propulsion unit universal drive assembly. The marine propulsion device has a flexible bellows surrounding the universal joint disposed between a marine engine and a sterndrive unit and is mounted to rotate with the universal joint itself. The universal joint is disposed within a chamber delineated by the bellows itself and by end caps mounted to the universal joint shafts. Supports for the universal joint bearings are constructed to permit free flow of fluid around the bearings. A quantity of lubricating oil is supplied to the chamber and at least partially fills the chamber when the latter is at rest. Upon driving rotation of the device, the bellows and universal joint and lubricating oil all rotate together. The resultant centrifugal force causes the oil to flow radially outwardly through the bearing supports to lubricate the bearings, with the oil forming a rotating mass engaging the inner bellows face. To support the bellows against the rotating mass, a helical spring is mounted externally of the bellows and within the bellows convolutions, with the spring being anchored adjacent both ends of the bellows. In addition, the bellows function as a finned heat radiator.
U.S. Pat. No. 4,940,434, which issued to Kiesling on Jul. 10, 1990, discloses a marine propulsion unit universal drive assembly with through-bellows exhaust. A marine propulsion device is provided wherein a pair of generally telescoped bellows surround the universal joint and provide an exhaust passage therebetween which communicates between the inboard engine and the sterndrive unit. In the embodiment disclosed, the inner bellows rotates with the universal joint while the outer bellows is stationary. The bellows are preferably of helical or spiral configuration and the rotating inner bellows forms an exhaust pump. In one embodiment, the bellows are concentrically disposed while in another embodiment the bellows are eccentrically mounted.
U.S. Pat. No. 5,083,952, which issued to Bland et al. on Jan. 28, 1992, describes a marine propulsion device exhaust system. A sterndrive unit comprising a gimbal housing which is adapted to be mounted on the transom of a boat and which has therein an exhaust water passage including a forwardly opening inlet, a rearwardly opening inlet, an exhaust conducting portion, a water conducting portion, and a water outlet communicating with the water conducting portion is disclosed.
U.S. Pat. No. 5,376,034, which issued to Meisenburg et al. on Dec. 27, 1994, discloses a marine drive exhaust system. A surfacing marine drive has a drive housing with a fore exhaust passage forward of the vertical bore housing the driveshaft, right and left exhaust passages extending rearwardly from the fore exhaust passage on opposite right and left sides of the vertical bore, and an aft exhaust passage extending rearwardly from the right and left exhaust passages and aft of the vertical bore and discharging exhaust into dual counter-rotating surface operating propellers.
U.S. Pat. No. 5,514,013, which issued to Rodskier on May 7, 1996, describes a boat propulsion unit. The propulsion unit is adapted to be suspended on the outside of a boat transom and drivably connected to an engine on the inside of the transom. The unit comprises a propeller driveshaft housing, a suspension arrangement adapted to be fixedly secured to the transom, a pivot which pivotally connects the driveshaft housing to the suspension arrangement to allow pivotal displacement of the driveshaft housing relative to the suspension arrangement about a pivot axis in a vertical plane and pivot axis in a horizontal plane, a steering device which is arranged to effect pivotal displacement of the driveshaft housing about first-mentioned axis, and a trim and tilt device which is arranged to effect pivotal displacement of the driveshaft housing about the second-mentioned axis.
U.S. Pat. No. 6,350,167, which issued to Neisen on Feb. 26, 2002, describes an inflatable transom seal and techniques for assembling such seal in a sterndrive. A transom seal assembly for sealing an opening in a boat transom is provided. A propulsion system has a part thereof extending through the transom opening. The seal assembly comprises an inflatable seal between respective peripheries of the part and the transom opening to provide water tight sealing relative to the interior of the boat even in the presence of a seal puncture condition.
The patents described above are hereby expressly incorporated by reference in the description of the present invention.